1. Field of the Invention
The present invention relates to a wireless transmission apparatus and related method, and more particularly, to a wireless transmission apparatus and related method for broadcasting data.
2. Description of the Prior Art
Generally speaking, point-to-point data transmission in a wireless local area network involves a wireless local area network access point (WLAN AP) transmitting packets to a receiving device. If the receiving device correctly receives a packet, the receiving device responds with an ACK signal to the wireless local area network access point. For this reason, if the wireless local area network access point does not receive the ACK signal within a predetermined period, this represents that the packet was not correctly received by the receiving device. Hence, the wireless local area network access point will retransmit the packet until the packet is correctly received or until the wireless local area network access point has abandoned the packet after retransmitting the packet a predetermined number of times. However, this kind of point-to-point data transmission is not suitable for broadcasting data, because the wireless local area network access point needs to consider whether each receiving device has responded to the ACK signal corresponding to the packet to select whether to retransmit the packet or to transmit a next packet. Thus, the wireless local area network access point must inquire with each receiving device whether the receiving device has received the packet correctly or not through a designating network address of each receiving device every time a transmission operation is completed. This significantly reduces available bandwidth of the wireless network. A data broadcast mechanism is disclosed in the prior art wherein the wireless local area network access point directly broadcasts the packet without considering whether the previous packet was correctly received when the wireless local area network access point operates in a broadcast mode. Although this kind of data broadcast method may not have problems when broadcasting general data, some receiving devices having poor receiving quality will possibly have a poor AV quality (for example, packet loss may cause video frames to suspend) when utilizing this kind of broadcast method to broadcast AV programs.
In addition, the bandwidth of wireless networks has recently reached to at least 20 Mbps; therefore, it is not a problem to broadcast one program to several receiving devices because only 6 Mbps bandwidth is occupied. However, when transmitting several AV programs, such as broadcasting a packet having three AV programs, the overall transmission bandwidth is limited by the receiving device not being able to correctly receive the packet due to not all the receiving devices being able to correctly receive the packet (for example, some receiving devices may not correctly receive the packet and need the wireless local area network access point to retransmit the packet frequently), which will result in other receiving devices being unable to successfully play received AV programs.